1. Field of the Invention
The present invention relates generally to medical methods, devices, and systems. In particular, the present invention relates to methods, devices, and systems for the endovascular or minimally invasive surgical repair of the valves of the heart, particularly the mitral valve.
Mitral valve regurgitation is characterized by retrograde flow from the left ventricle of a heart through an incompetent mitral valve into the left atrium. During a normal cycle of heart contraction (systole), the mitral valve acts as a check valve to prevent flow of oxygenated blood back into the left atrium. In this way, the oxygenated blood is pumped into the aorta through the aortic valve. Regurgitation of the valve can significantly decrease the pumping efficiency of the heart, placing the patient at risk of severe, progressive heart failure.
Mitral valve regurgitation can result from a number of different mechanical defects in the mitral valve. The valve leaflets, the valve chordae which connect the leaflets to the papillary muscles, or the papillary muscles themselves may be damaged or otherwise dysfunctional. Commonly, the valve annulus may be damaged, dilated, or weakened limiting the ability of the mitral valve to close adequately against the high pressures of the left ventricle.
The most common treatments for mitral valve regurgitation rely on valve replacement or strengthening of the valve annulus by implanting a mechanical support ring or other structure. The latter is generally referred to as valve annuloplasty. A recent technique for mitral valve repair which relies on suturing adjacent segments of the opposed valve leaflets together is referred to as the xe2x80x9cbow-tiexe2x80x9d or xe2x80x9cedge-to-edgexe2x80x9d technique. While all these techniques can be very effective, they usually rely on open heart surgery where the patient""s chest is opened, typically via a sternotomy, and the patient placed on cardiopulmonary bypass. The need to both open the chest and place the patient on bypass is traumatic and has associated morbidity.
For these reasons, it would be desirable to provide alternative and additional methods, devices, and systems for performing the repair of mitral and other cardiac valves, particularly the tricuspid and aortic valves. Such methods, devices, and systems should preferably not require open chest access and be capable of being performed either endovascularly, i.e., using devices which are advanced to the heart from a point in the patient""s vasculature remote from the heart or by a minimally invasive approach. Still more preferably, the methods, devices, and systems should not require that the heart be bypassed, although the methods, devices, and systems should be useful with patients who are bypassed and/or whose heart may be temporarily stopped by drugs or other techniques. At least some of these objectives will be met by the inventions described hereinbelow.
2. Description of the Background Art
Minimally invasive and percutaneous techniques for coapting and modifying mitral valve leaflets to treat mitral valve regurgitation are described in WO 98/35638; WO 99/00059; WO 99/01377; and WO 00/03759.
Maisano et al. (1998) Eur. J. Cardiothorac. Surg. 13:240-246; Fucci et al. (1995) Eur. J. Cardiothorac. Surg. 9:621-627; and Umana et al. (1998) Ann. Thorac. Surg. 66:1640-1646, describe open surgical procedures for performing xe2x80x9cedge-to-edgexe2x80x9d or xe2x80x9cbow-tiexe2x80x9d mitral valve repair where edges of the opposed valve leaflets are sutured together to lessen regurgitation. Dec and Fuster (1994) N. Engl. J. Med. 331:1564-1575 and Alvarez et al. (1996) J. Thorac. Cardiovasc. Surg. 112:238-247 are review articles discussing the nature of and treatments for dilated cardiomyopathy.
Mitral valve annuloplasty is described in the following publications. Bach and Bolling (1996) Am. J. Cardiol. 78:966-969; Kameda et al. (1996) Ann. Thorac. Surg. 61:1829-1832; Bach and Bolling (1995) Am. Heart J. 129:1165-1170; and Bolling et al. (1995) 109:676-683. Linear segmental annuloplasty for mitral valve repair is described in Ricchi et al. (1997) Ann. Thorac. Surg. 63:1805-1806. Tricuspid valve annuloplasty is described in McCarthy and Cosgrove (1997) Ann. Thorac. Surg. 64:267-268; Tager et al. (1998) Am. J. Cardiol. 81:1013-1016; and Abe et al. (1989) Ann. Thorac. Surg. 48:670-676.
Percutaneous transluminal cardiac repair procedures are described in Park et al. (1978) Circulation 58:600-608; Uchida et al. (1991) Am. Heart J. 121:1221-1224; and Ali Khan et al. (1991) Cathet. Cardiovasc. Diagn. 23:257-262.
Endovascular cardiac valve replacement is described in U.S. Pat. Nos. 5,840,081; 5,411,552; 5,554,185; 5,332,402; 4,994,077; and 4,056,854. See also U.S. Pat. No. 3,671,979 which describes a catheter for temporary placement of an artificial heart valve.
Other percutaneous and endovascular cardiac repair procedures are described in U.S. Pat. Nos. 4,917,089; 4,484,579; and 3,874,338; and WO 91/01689.
Thoracoscopic and other minimally invasive heart valve repair and replacement procedures are described in U.S. Pat. Nos. 5,855,614; 5,829,447; 5,823,956; 5,797,960; 5,769,812; and 5,718,725.
The present invention provides methods, devices, and systems for the endovascular repair of cardiac valves, particularly the atrioventricular valves which inhibit back flow of blood from a heart ventricle during contraction (systole), most particularly the mitral valve between the left atrium and the left ventricle. By xe2x80x9cendovascular,xe2x80x9d it is meant that the procedure(s) of the present invention are performed with interventional tools and supporting catheters and other equipment introduced to the heart chambers from the patient""s arterial or venous vasculature remote from the heart. The interventional tools and other equipment may be introduced to the vasculature percutaneously, i.e., through an access sheath placed through the skin, or may be introduced via a surgical cut down, and then advanced from the remote access site through the vasculature to the heart. Thus, the procedures of the present invention will generally not require penetrations made directly through the exterior heart muscle, i.e., myocardium, although there may be some instances where penetrations will be made interior to the heart, e.g., through the interatrial septum to provide for a desired access route. While the procedures of the present invention will usually be percutaneous and intravascular, many of the tools will find use in minimally invasive and open surgical procedures as well. In particular, the tools for repositioning the valve leaflets prior to attachment can find use in virtually any type of procedure for modifying cardiac valve function.
Although the methods, devices, and systems of the present invention may be used for the endovascular repair of any of the cardiac valves, the majority of the description will be in regards to the repair of atrioventricular valves. The atrioventricular valves are located at the junctions of the atria and their respective ventricles. The atrioventricular valve between the right atrium and the right ventricle has three valve leaflets (cusps) and is referred to as the tricuspid or right atrioventricular valve. The atrioventricular valve between the left atrium and the left ventricle is a bicuspid valve having only two leaflets (cusps) and is generally referred to as the mitral valve. In both cases, the valve leaflets are connected to the base of the atrial chamber in a region referred to as the valve annulus, and the valve leaflets extend generally downwardly from the annulus into the associated ventricle. In this way, the valve leaflets open during diastole when the heart atria fills with blood, allowing the blood to pass into the ventricle. During systole, however, the valve leaflets are pushed together and closed to prevent back flow of blood into the atria. Thus, the valve leaflets each have generally two planar surfaces, a surface facing the atrium which may be referred to as the atrial surface and a surface facing the ventricle which may be referred to as the ventricular surface. Such terminology may be used with cardiac valves which do not straddle an atrium and a ventricle. In these cases, it is understood that such terminology may be used to suitably describe the corresponding valve surfaces.
Alternatively, the surfaces of the valves may be described in relation to flow direction. For example, since valve leaflets each have two planar surfaces, a surface facing upstream may be referred to as the upstream surface and a surface facing downstream may be referred to as the downstream surface. In the case of the mitral valve, the atrial surface would be the upstream surface and the ventricular surface would be the downstream surface. In the case of the aortic valve, the ventricular surface would be the upstream surface and the surface facing the aorta would be the downstream surface. Such terminology may be most relevant when considering the natural shape of the leaflets since the shape is more related to direction of flow than orientation of the valve in the heart.
Interventions according to the present invention are generally directed at the valve leaflets. It will be the general purpose of such interventions to modify the manner in which the valve leaflets coapt or close during systole so that back flow or regurgitation is minimized or prevented. While the procedures of the present invention will be most useful with the atrioventricular valves, at least some of the tools described hereinafter may be useful in the repair of other cardiac valves, particularly the aortic valve.
The methods of the present invention will usually include accessing a patient""s vasculature at a location remote from the heart and advancing an interventional catheter having a capturing device through the vasculature to a location near a cardiac valve to be repaired. The methods may include applying an upward force against a downstream surface of at least one leaflet of the cardiac valve with the capturing device. Such application of force will reposition at least one leaflet so as to reduce leakage through the valve during ventricular systole. Typically, two or more leaflets are repositioned in this manner to achieve desired coaptation. The interventional tool may comprise an elongate shaft having a proximal end and a distal end wherein the capture device is disposed near the distal end. The capture device may comprise at least one distal element capable of protruding radially outward from the shaft. The above described application of force may be achieved by pressing a distal element of the capture device against the downstream surface of the leaflet.
In a first aspect of the methods of the present invention, the distal element may be adjusted prior to or after pressing the distal element against the surface of the leaflet. Such adjustment may include adjusting the length of protrusion of the distal element from the shaft. This may be achieved by retracting or extending the distal element. This allows the capture device to be advanced to the valve in a low profile arrangement and the distal elements to be extended for use once the capture device has been positioned in a desired orientation in relation to the valve. When adjustment of the length is performed after the distal element is in contact with the valve leaflet, such adjustment may serve to reposition the valve leaflet. In addition, adjustment may include adjusting the curvature of the distal element. Adjustment of the curvature may also be achieved by retracting or extending the distal element. Again, if this adjustment step is performed after the distal element is in contact with the leaflet, such adjustment in curvature may serve to reposition the valve leaflet. In some embodiments, the capture device may optionally comprise at least one proximal element capable of protruding radially outward from the shaft and the methods of the present invention may further include holding one or more leaflets between the proximal and distal elements. In this case, adjusting the length and/or curvature of the proximal or distal elements may serve to reposition the captured valve leaflets. Such adjustment of the proximal and distal elements may be achieved simultaneously. In an additional aspect, the proximal and distal elements may interlock for added grasping strength.
In a second aspect of the methods of the present invention, flow through the valve may be observed to determine if regurgitation has been inhibited by the leaflet repositioning. Such observation may be achieved by any suitable means. If the regurgitation has not been sufficiently inhibited, the application of upward force on at least one valve leaflet with the capturing device may be adjusted. This may be achieved with any of the adjustment steps previously described and/or by decreasing or removing any of the upward force against one or more valve leaflets. The observation and adjustment steps may be repeated any number of times until the regurgitation has been sufficiently inhibited.
In a third aspect of the methods of the present invention, the leaflets may optionally be fixed together. Fixing may include fastening, suturing, clipping, stapling, riveting, gluing, or fusing the leaflets together. Alternatively, the capturing tool may be detached from the interventional tool to serve as a fixation device. This involves activating a detachment or decoupling mechanism which allows the capture tool to separate from the interventional tool to be left behind as a permanent implant.
In a fourth aspect of the methods of the present invention, one or more valve leaflets may be atraumatically captured with the capturing device and the captured leaflets may be repositioned independently of each other. When the capture device comprises at least one distal element capable of protruding radially outward from the shaft, a leaflet may be atraumatically captured by pressing the distal element against the leaflet surface. The captured leaflets may be independently repositioned by independently adjusting the distal elements. Likewise, when the capture device comprises at least one proximal element and one distal element, each capable of protruding radially outward from the shaft, the atraumatically capturing step comprises holding the leaflet between the proximal and distal elements. The captured leaflets may be independently repositioned by simultaneously retracting or extending the proximal element and distal element disposed on opposite sides of the leaflet. Again, once the leaflets have been repositioned to a desired orientation, the leaflets may be fixed together by any suitable means including detaching the capture device from the interventional tool and leaving it behind.
In a fifth aspect of the methods of the present invention, the valve leaflets, each leaflet comprising a proximal side and a distal side, may be repaired with the use of sutures having attached anchors. To begin, a first leaflet may be penetrated from the proximal side to the distal side of the leaflet with a penetrating device. In this case, at least a portion of first anchor having a first attached suture is then deployed on the distal side of the first leaflet. A second leaflet is penetrated from the proximal side to the distal side with a penetrating device. Such a penetrating device may be the same penetrating device as penetrated the first leaflet or a separate penetrating device. At least a portion of a second anchor having a second attached suture is deployed on the distal side of the second leaflet. The first and second sutures are then secured together. By securing the sutures together, the valve is repaired by fixing the leaflets together in the desired coapted orientation. Typically, the anchors are disposed in or on the penetrating devices. For example, the anchors may be loaded within a lumen in the penetrating devices or mounted externally on a penetrating device. In any case, the deploying steps comprise releasing the anchors from the respective penetrating devices. In many cases, the anchors are expanded to provide anchoring support on the distal side of the leaflet to prevent the anchor from passing through the penetration and releasing the suture. The anchors may be self-expanding or the deploying steps may further comprise expanding the anchors.
As an alternative, anchors may be used simply to aid in the placement of sutures wherein the anchors are removed prior to securing the sutures together. In this case, again, a first leaflet is penetrated from the proximal side to the distal side of the leaflet with a penetrating device. And, at least a portion of a first anchor having a first attached suture is deployed on the distal side of the first leaflet. The first leaflet is again penetrated from the proximal side to the distal side with a penetrating device, however, this time at a new location. At this new location, a snare is deployed on the distal side of the leaflet so that the snare captures at least part of the first anchor. The snare is then retracted so that the anchor is drawn through the penetration of the snare. By drawing the anchor through the penetration to the proximal side of the leaflet, the suture line effectively passes from the proximal side of the leaflet through a penetration to the distal side traversing a portion of the distal side of the leaflet and then passing through a separate penetration back to the proximal side of the leaflet. This may be repeated on a second leaflet in a similar manner. The four portions of suture on the proximal side of the leaflets may then be secured together. This method may be repeated at any number of locations on the leaflet to create any number of suture lines on the proximal side of the leaflet for securing together. Additional suture lines may provide added fixation strength or possible repositioning of the leaflets. Likewise, the anchor and snare may be deployed on separate leaflets, respectively, so that a suture line may penetrate a first leaflet from the proximal side to the distal side traverse on the distal side of the leaflet to a second leaflet and then cross back through a penetration on the second leaflet to the proximal side. One or more sutures may be positioned in this manner and secured together as previously described. Also, it may be appreciated that such suture placement may be achieved on the opposite side of the leaflets so that the sutures are secured on the distal side of the leaflets.
The penetrating devices described above may be advanced through guide conduits on the interventional tool. Such guide conduits may be adjusted to direct the penetrating device toward the desired location on the valve leaflet. Adjustment may include extending or retracting the guide conduits or angularly adjusting the guide conduits in relation to the shaft. When the capture device comprises at least one loop which is protrudable radially outward from the shaft, the guide conduit may be positioned so that the conduit guides the penetration device through the loop when the penetration device is advanced. Once the penetrating device has penetrated the leaflet, the loops may be retracted to radially translate the penetration devices and the penetrated leaflets toward the shaft. This may serve to reposition the leaflets in a more desired coapted orientation.
The devices of the present invention will usually include an interventional catheter configured to pass from the remote vasculature of a patient to a position within the heart adjacent to the cardiac valve to be repaired and a capture device on the interventional catheter for capturing at least one valve leaflet. Typically, the capture device includes at least one distal element and optionally includes at least one proximal element. The distal end or proximal elements may be comprised of a number of materials, including wire, ribbon, filaments, or fibers which are made from stainless steel, metals, nitinol, shape memory alloy, polymers, silk, polyester or nylon, to name a few.
In a first aspect of the devices of the present invention, the distal elements of the capture devices may take a number of forms and these forms can take a number of shapes. In a preferred embodiment, the distal elements have the form of loops. The loops may have a petal shape so that when the loops are positioned on opposite sides of the shaft, the loops will form a xe2x80x9cfigure 8xe2x80x9d shape when viewed from the top or bottom. This loop configuration is most suitable for use with valves having two leaflets. It may be appreciated that more than two loops may be present and arranged around the shaft having various distances between the loops. Thus, the looped distal elements may be configured for valves having three leaflets. In another embodiment, the distal element has the form of a block, rod or bar disposed perpendicularly to the shaft. The bar may pivot around a pivot point at the base of the shaft to manipulate the position of the bar. Such manipulation may be achieved with the use of a pullwire extending from the shaft to the bar. Retracting or pulling upwards on the pullwire may pivot the bar around the pivot point. Such pivoting orients the bar to a low profile position so that the interventional tool may more easily be passed through a guide catheter, and further between a set of valve leaflets so that the bar is disposed below the valve. The bar may then be pressed against the downstream surface of the leaflets to grasp and reposition the leaflets.
In a second aspect of the devices of the present invention, the distal elements may be individually repositionable or adjustable. The elements may be extended or retracted by variable amounts for protrusion of various distances from the shaft. Such extension and retraction may also adjust the width of the exposed elements if the width varies radially from the shaft, such as with a petal shape. Further, the elements may have differing angles of curvature. This may be achieved by heat-shaping the elements to have different curvatures, or the curvatures may be adjusted by manipulation by the user. Individual manipulation of the elements allows individually protruding the elements prior to capturing the leaflets to ensure proper orientation and includes individually adjusting the elements after grasping the leaflets to reposition the leaflets. In addition, it may be appreciated that the elements may be extended and retracted simultaneously, if desired.
In a third aspect of the devices of the present invention, the interventional tool comprises proximal elements which are capable of protruding radially outward from the shaft at a location which is proximal to the distal elements. The proximal elements may have any of the forms, shapes, material compositions, features or capabilities described in relation to the distal elements. Thus, the proximal elements may be extended, retracted or similarly adjusted to further orient the captured leaflets. The proximal elements may be deployed separately from the distal elements. For example, the proximal elements may be constrained within a shaft while the distal elements are extended radially outward. The proximal elements may then be released by retracting the shaft. Release of the proximal elements allows them to extend radially outward and downward to contact the valve leaflet. In this arrangement, the valve leaflets are held between the proximal and the distal elements. To assist in holding the leaflets the proximal and/or distal elements may included various friction accessories, such as prongs or windings around the elements such as bands or barbs. Alternatively or in addition, the proximal elements and distal elements may interlock to prevent relative motion between the elements and more securely hold the leaflets.
In some embodiments, the proximal and distal elements are formed from a continuous structure. The continuous structure may be held in a low profile position under tension. When the continuous structure is released and allowed to relax, the reforming of the structure allows the structure to protrude outward at various points along the structure. Each protrusion is similar to an above-described proximal or distal element and functions in a similar manner.
In a fifth aspect of the devices of the present invention, the interventional catheter may include a fixation tool or device. In one embodiment, the capture device may function as a fixation device when left in place. To this end, the capture device may be detachable and be left behind as a permanent or temporary implant. Detachment may be achieved by a variety of different mechanisms and design features.
In other embodiments, the fixation tools are used with the capture device either incorporated into the interventional tool or used in combination with the interventional tool. In many of these embodiments, the fixation tools are advanceable through guide conduits disposed near the distal end of the interventional tool. The guide conduits are used to guide the fixation tools to specific locations on the surfaces of the leaflets. The guide conduits are located proximal to the distal elements and are capable of extending and retracting axially and angularly outward from the shaft. Any angle may be used to target the leaflets at points which are approximately one to twelve millimeters inward or away from the free edge of each leaflet. Typically, the guide conduit is used to introduce a fixation tool comprising a penetrating device or needle. The needle may house a suture having an anchor disposed at the distal end of the suture. The needle is advanced toward a valve leaflet to penetrate the leaflet and emerge from the other side. The anchor may be deployed on the opposite side of the leaflet by passing the anchor through the needle and expanding or allowing it to self-expand after it has exited the needle. Alternatively, the anchor may be mounted on the outside of the needle and covered by a sheath. Retraction or removal of the sheath would allow expansion of the anchor. In any case, after anchor deployment, the needle is then retracted while maintaining the anchor on the distal side of the leaflet. A number of different types of anchors may be used during fixation of the leaflets. Typically the anchor is expandable from a compressed, low profile state, for delivery to the anchoring site, to an expanded state to provide a large enough surface for anchoring support. In addition, the fixation tools may include snares which are deployable on the distal side of the leaflet for capturing at least part of an anchor. The snare may then be retracted to move the anchor, such as to draw the anchor through a penetration in the leaflet. Once the suture is placed through the leaflets, either attached to anchors or free from anchors, the suture ends or lines may then be fixed together by conventional knot tying or any suitable method, including positioning suture fasteners.
The methods, devices and systems of the present invention may be provided in one or more kits for such use. The kits may include an interventional catheter configured to pass from the remote vasculature of a patient to a position within the heart adjacent to a cardiac valve to be repaired, wherein the catheter has a capture device comprising at least one distal element, and instructions for use. The instructions for use may set forth any of the methods of the present invention. Optionally, such kits may further include any of the other systems components described in relation to the present invention and any other materials or items relevant to the present invention.